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Study: Are wearable activity monitors effective?

Assistant professor Mia Cajita reviewed 61 studies with interventions using wearable activity monitors Heading link


Wearable activity monitors, such as Fitbits or Garmin watches, are ubiquitous as people try to achieve better health outcomes by vigilantly tracking steps, sleep and calories. One recent survey found that one-eighth of U.S. adults use them.

But after a review of 61 academic studies, UIC Nursing assistant professor Mia Cajita, PhD, BSN ’12, RN-BC, found she could not determine the efficacy of interventions using the devices to increase physical activity, decrease sedentary behavior and improve sleep. Cajita was lead author on the paper published online in January in the peer-reviewed journal, Current Epidemiology Reports.

“What we found out is the majority of our studies that were included in this review were feasibility studies,” she says. “They were not intended to test the actual efficacy of the device or the intervention that’s using the device. Because of that, we can’t really say that the devices are effective in changing behavior.”

She added that many of the studies showed potential for increasing physical activity and decreasing sedentary time, but most were pilot studies. They were not on a large enough scale and did not control for other factors in order to draw definitive conclusions. Sleep was a particularly unexplored area, she said.

“If you have a small study, you may see a signal—the potential—that it could be efficacious, but you can’t categorically say the effect is due to the intervention, since there are other factors that could contribute to changes,” she says.

The paper called for “more rigorous study designs and adequate sample sizes” to establish the efficacy of wearable activity monitor-based studies.

The novelty effect

The paper, “Feasible but Not Yet Efficacious: A Scoping Review of Wearable Activity Monitors in Interventions Targeting Physical Activity, Sedentary Behavior and Sleep,” looked at studies published between 2009 and 2019 that used direct-to-consumer wearable activity monitors to conduct interventions. The majority used wrist-worn Fitbit models (although all but one is now discontinued due to the fast-changing nature of the technology).

Cajita noted a widespread “novelty effect” across the studies. She says the device sparked a change in behavior initially, but once the novelty of the device wore off, people went back to their old routines.

“What was interesting and kind of disheartening to me was that, in the studies that did follow-up interviews, the majority of participants said they liked the device and thought it was easy to use,” she says. “They had no complaints whatsoever. Yet, that didn’t translate to continued use.”

She cited one study where participants were given a cash incentive to increase physical activity for six months. That group performed better than groups that received no monetary incentive, but once the cash reward was removed, the participants lost motivation.

“More research is needed to see how we can intrinsically motivate people to actually change their behavior,” she says. “While the device might help, it’s ultimately up to the individual person if they’re really willing to change their behavior.”

The paper was co-authored by the University of Pittsburgh’s Christopher E. Kline, Lora E. Burke, Evelyn G. Bigini and Christopher C. Imes. Rebecca Raszewksi, MS, AHIP, UIC reference librarian, helped develop the electronic search strategy.